Fine structures such as microstructures and nanostructures may be applied to various fields such as photonic materials, micro-electromechanical systems (MEMS), biomaterials, self-assembly and so on. Recently, as a technique for producing such fine structures, continuous-flow lithography has been proposed (D. Dendukuri, D. Pregibon, J. Collins, T. Hatton, P. Doyle. “Continuous-flow lithography for high-throughput microparticle synthesis.” Nature materials, vol. 5, pp. 365-369, 2006; U.S. Patent No. 2007-0105972, Microstructure synthesis by flow lithography and polymerization). The continuous-flow lithography involves flowing a photocurable fluid into a microfluidic channel, exposing the photocurable fluid to a predetermined shape of light to selectively cure the photocurable fluid, and continuously producing various kinds of free-floating microstructures. When the continuous-flow lithography is used, microstructures having various shapes, sizes, and chemical compositions can be produced more quickly and easily.
However, the continuous-flow lithography proposed in the above paper can produce only single-layered microstructures. Therefore, it is difficult to produce three-dimensional microstructures with a complex structure. Further, the continuous-flow lithography proposed in the above paper, uses a photomask, which is not programmable in real time. Therefore, the continuous-flow lithography has a limited time-and-space flexibility in producing microstructures.